An ascendant Vladimir Putin is dismantling the Ukraine and absorbing its eastern territory in the Crimea. President Obama is fighting back against critics that his administration serially projected weakness, and thereby lost the ability to deter rogue regimes. Obama, of course, rejects the notion that his own mixed signals have emboldened Putin to try something stupid that he might otherwise not have. After all, in terms of planes, ships, soldiers, nuclear strength, and economic clout, Putin must concede that he has only a fraction of the strength of what is at the disposal of the United States.

In the recriminations that have followed Putin's daring intervention, Team Obama has also assured the international community that Putin is committing strategic suicide, given the gap between his ambitions of expanding the Russian Federation by threats of force and intimidation, and the rather limited means to do so at his disposal. Perhaps Putin is pandering to Russian public opinion or simply delusional in his wildly wrong calculations of all the bad things that may befall him.

Do any of those rationalizations matter-given that Putin, in fact, did intervene, plans to stay in the eastern Ukraine, and has put other former member states of the former Soviet Union on implicit notice that their future behavior may determine whether they too are similarly absorbed?

History is replete with examples of demonstrably weaker states invading or intervening in other countries that could in theory or in time bring to their defense far greater resources. On September 1, 1939, Hitler was both militarily and economically weaker than France and Britain combined. So what? That fact certainly did not stop the Wehrmacht over the next eight months from invading, defeating, and occupying seven countries in a row.

Hitler was far weaker than the Soviet Union. Still, he foolishly destroyed his non-aggression pact with Stalin to invade Russia on June 22, 1941. Next, Nazi Germany, when bogged down outside Moscow and having suffered almost a million casualties in the first six months of Operation Barbarossa, certainly was weaker than the United States, when Hitler idiotically declared war on America on December 11, 1941.

Yet all those demonstrably stupid moves did not prove that Hitler himself agreed that that he was weaker than his targets. Much less did Nazi Germany have any good reason from recent experiences to accept the fact that it was weaker than were its enemies. Even Neville Chamberlain did not claim that Hitler had invaded Poland because he was weaker than France and Britain-though again he probably was.

From Benito Mussolini's invasions in 1940-41 of France, the Balkans, and Greece to Argentine Gen. Galtieri's attack on the Falklands in 1982 and Saddam Hussein's entry into Kuwait in the summer of 1990, there are plenty of examples of weak states attacking countries who have alliances or friends far stronger than the attacker. Why then do the Putins of the past and present try something so shortsighted-as the Obama administration has characterized the Ukraine gambit?

Answer? Strength is in the eye of the attacker.

What might prove to be demonstrably stupid in the future, or even seems foolish in the present, may not necessarily be so clear to the attacker. The perception, not the reality, of relative strength and weakness is what guides aggressive states.

Obama looks to logic, reason, and morality in his confusion over why Putin did something that cannot be squared away on any rational or ethical calculators.

Putin, however, has a logic of his own. American intervention or non-intervention in particular crises is not just the issue for Putin. Instead he sees fickleness and confusion in American foreign policy. He has manipulated and translated this into American impotence and thus reigns freely on his borders.

Red lines in Syria proved pink. Putin's easily peddled his pseudo-WMD removal plan for Syria. America is flipping and flopping and flipping in Egypt. Missile defense begat no missile defense with the Poles and Czechs. Lead from behind led to Benghazi and chaos. Deadlines and sanctions spawned no deadlines and no sanctions with Iran. Then there was the reset with Russia. Obama's predecessors, not his enemies were blamed. Iraq was cut loose. We surged only with deadlines to stop surging in Afghanistan. Loud civilian trials were announced for terrorists and as quietly dropped. Silly new rubrics appeared like overseas contingency operations, workplace violence, man-caused disasters, a secular Muslim Brotherhood, jihad as a personal journey, and a chief NASA mission being outreach to Muslims.

Putin added all that up. He saw a pattern of words without consequences, of actions that are ephemeral and not sustained, and so he concluded that a weaker power like Russia most certainly can bully a neighbor with access to stronger powers like the United States. For Putin and his ilk, willpower and his mythologies about Russian moral superiority are worth more than the hardware and data points of the West.

To return to our previous topic: Hitler finally went into Poland and Western Europe because he believed that even if his opponents collectively were stronger, there was no evidence in the immediate past-in the Rhineland, during the Anschluss, or amid the Czechoslovakia annexations-that they would either act individually or in concert to stop his aggression. The Nazis' cynical pact with the Soviet Union secured his eastern front, and cemented the impression that he could beat all of Western Europe-whose aggregate planes, tanks, artillery, and armies were nevertheless greater than Germany's.

Hitler invaded a far stronger Soviet Union because he was convinced that its purges of high-ranking officers, that its recent lackluster military performance in Finland and Poland in 1939, that the unstoppable record theretofore of Blitzkrieg in 1930-40, and that the collapse of Russia in 1917, all suggested Russia's greater relative strength was now a chimera.

Similar reasoning led Hitler to declare war on the United States. In the abstract, Hitler knew that during World War I, in just over a year, an earlier, weaker America had sent well over 1 million soldiers to Europe to stop the Kaiser's spring offensive of 1918, and eventually overwhelmed Imperial Germany with its industrial output. But Hitler also figured that a different U.S. had stood idly by in 1940 while Britain, its closet ally, burned, that it would have its hands full with a two-front war against the Japanese navy, and that prior U.S. isolationism meant that it would not rally to war as it had in 1917. Above all, Hitler did not just rely on relative material strength, but believed the iron will of Nazi ideology could make up the divisions he lacked on the Eastern front or in the war with America. And so he did something fundamentally stupid in declaring war on a much stronger U.S.

The Argentines in 1982 dared the naval successors to Lord Nelson to fight by sea, on the silly idea that Margaret Thatcher, Britain's first female Prime Minister, lacked the machismo to protect some far off windswept rocks in the south Atlantic. The junta in Argentina remembered that some prominent British politicians had parroted the Argentine name "Malvinas" for the Falkland's, and that the reset faction in Britain had earlier withdrawn a few unimpressive warships from the Falkland's. In the junta's view, a far stronger Britain was too smug and too sophisticated to worry about loud noise emanating from a caricatured two-bit dictatorship in Buenos Aires, pandering to the public to hide its own domestic incompetency. Once again, a dictator counted on supposed willpower and superior morale to substitute for the material strength he lacked.

Ditto Saddam Hussein in August 1990. He did not need Kuwait's oil. Taking it might likely ensure a coalition of far stronger and wealthier powers arrayed against him. But such a short-sighted move did not appear so short-sighted to Saddam as he ordered his tanks into Kuwait City. Saddam figured that the U.S. Ambassador to Iraq, April Glaspie, had casually assured him that border disputes among Arab states were not of much interest to Washington. Saddam assumed that the eroding Soviet Union might still have enough clout to back his gamble. He reasoned that no one had cared when he had invaded Iran or gassed the Kurds, so why would they care now? He thought the opulent Persian Gulf States were softies compared to his Republican Guard who had died in droves in Iran. And George H.W. Bush was an unknown quantity.

Deterrence is an art, not a science. And it is transitory, often psychological, and as easily lost as it is hard to regain. Weak states invade others with strong backers because they are not deterred and feel they can get away with it-and thereby become stronger by their sheer success. If they fail, it is usually because they or their intended targets had originally misjudged relative power. Some sort of hostilities then ensue to correct those inaccurate initial appraisals. Peace follows when everybody again knows who was truly weak and who was strong in the first place.

When Putin clearly learns that the United States was all long the stronger power, and remains the far stronger power, and that Russia, for all its blather about the greater will and spirit, was and remains the weaker party, he will be deterred and recede. Then calm will return.

In contrast, if Putin continues to meddle in Ukraine and meets no consequences, then he was probably correct that for all the impressive military force of the United States, for all its economic power, for all its global influence and array of international allies, it really is retreating from the international stage.

In some sense, Putin defines power not by tanks or GDP, but by a state's willingness to gamble to use whatever power it has. He assumes that others less reckless than he would rather rationalize their unwillingness to use their superior economic and military assets than run the risks of employing them. For an aggressive but weaker belligerent, its sheer audacity, indeed its recklessness is seen as a force multiplier-an unfathomable asset that sometimes makes up the difference in what is lacking in bombers or cash. By that standard, a weak Putin believes that he's strong and assumes anyone more powerful who disagrees will not prove it. It is up to others to disabuse him of that folly.

Victor Davis Hanson, the Martin and Illie Anderson Senior Fellow at the Hoover Institution, is a classicist and an expert on the history of war.